1. Field of the Invention
The present invention relates to a pin fastener. More particularly, the invention relates to a pin fastener for fastening a pin provided on a personal ornament or the like. The invention is preferably applied to a pinning device for an ornament such as a tie tack, a pin brooch, an earring, or a necklace, but is also applied to a pinning device for any kind of article with a comparatively small size other than an ornament.
2. Description of the Related Art
Many of recent pin fasteners have a structure in which an advancement and withdrawal of a fastening member with respect to a pin are carried out by utilizing a spring material having an elastic deformation function. As a normal pin fastener is of a small size, it is practical to simplify the structure of the fastener with a pin fastening mechanism utilizing the spring material.
For example, a pin fastener shown in cross-section in FIGS. 1(a) and 1(b) is proposed as a first related art. In the pin fastener 1, a pair of fastening members 3 made of an elastically deformable material are housed inside a cover 2 with a circular or ellipsoidal form as a whole. The fastening members 3 are configured so as to be symmetrical with a central pin insertion portion 4 as a center, and each of them includes a pin fastening arm 5 and a holding arm 6, each of which has the form shown in the drawing.
In a condition in which a pin is fastened, as shown in FIG. 1(a) , the holding arm 6 of one of the two fastening members 3 presses the other fastening member 3 in an opposite direction, as a result of which the pair of pin fastening arms 5 are pressed in the direction of the pin insertion portion 4. For this reason, the pin (not shown) in the pin insertion portion 4 is fastened by the pair of pin fastening arms 5.
When the pin is withdrawn from the pin fastener 1, button portions 7 projecting outside the cover 2 from the fastening members 3 are depressed in the direction of the center. Then, as shown in FIG. 1(b) , each of the pair of pin fastening arms 5 withdraws from the pin against the biasing force of the holding arm 6, and the condition in which the pin is fastened is terminated.
Next, a personal ornament fastener described in the following Patent Literature 1 is illustrated as a second related art.    [Patent Literature 1] JP-A-2008-394
The fastener is such that, although not shown, firstly, a guide cylinder on the inside wall surface of which a tapered portion is formed is provided in a housing having a pin insertion opening. Then, a spherical body pressing member which has a plurality of spherical bodies and a flange member whose lower surface makes contact with the spherical bodies, and is constantly biased in the direction of the pin insertion opening by an elastic body, is disposed in the inside space of the guide cylinder. As a result of this, a configuration is such that the pin is clamped inside a ring formed by the plurality of spherical bodies ma predetermined internal position of the tapered portion.
However, a pin fastener of a personal ornament or the like is generally of a very small size. Therefore, The first related art shown in FIG. 1 and the second related art exemplified as Patent Literature 1 both have an intricate structure, and moreover, it is not easy with them to manufacture or assemble parts.
That is, with the first related art, the pair of fastening members 3 include the pin fastening arms 5 and holding arms 6 with an intricately bent form, and it is not easy to accurately manufacture these kinds of intricately formed fastening member 3 to a microscopic size. Also, with the second related art, it is not easy to provide the guide cylinder haying the tapered portion on its inside wall surface in the minute housing, or dispose the plurality of spherical bodies, flange member, elastic body (a coil spring), and the like, in the inside space of the guide cylinder, both in terms of manufacturing the parts and in terms of assembling the parts. Consequently, in the cases of these pin fasteners, manufacturing cost and assembly cost are forced upward.